Chronic heart failure is a disease in which the heart cannot maintain an adequate cardiac output to various organs due to reduced myocardial contractility, and conventional therapies therefor include the use of cardiac stimulants that increase myocardial contractility such as digitalis and xanthine drugs. However, these drugs have been shown to adversely affect vital prognosis as a result of increased consumption of myocardial energy during prolonged administration. Recently, therapies with β-blockers or ACE inhibitors have prevailed that reduce overload on the heart caused by over activation of the sympathetic nervous system or the renin-angiotensin system in patients with heart failure. However, long-term vital prognosis of patients with heart failure is still poor and it would be desirable to develop a drug for treating heart failure based on a new mechanism.